The present invention relates to a II-VI compound semiconductor light emitting device and, more particularly, to a visible light emitting diode and a laser diode.
In conventional group II-VI light emitting devices formed on an InP substrate, as disclosed in Japanese Patent Laid-Open Nos. 2-125477 and 5-21892, to efficiently emit light by injection of a current a double hetero structure is formed by using a ZnCdSeTe, MgZnCdSe, or MgZnSSe mixed crystal in a clad layer. Also, as disclosed in Japanese Patent Laid-Open No. 7-94832, a ZnCdSe mixed crystal is used to decrease the resistance of a p-type electrode.
Unfortunately, these conventional II-VI light emitting devices have a large device resistance and a low light emission efficiency. This is so because the band gap of a ZnCdSeTe mixed crystal is not so large as to strongly confine carriers. Also, p-type doping for ZnCdSe, MgZnCdSe, or MgZnSSe mixed crystals are difficult. Consequently, the hole concentration cannot be increased to 1.times.10.sup.17 cm.sup.-3 or more.